珠海海积软土孔隙分布与应力水平的关系研究

Relationship Between Entrance Pore Distribu-tion and Stress Level of Marine Clay in Zhuhai

采用压汞法研究了不同固结压力作用下具有强结构性的珠海海积软土的微观孔隙入口孔径分布与应力水平的关系，通过X-射线衍射试验（XRD）对其黏土矿物含量进行定量分析，并与加拿大Regina黏土进行了对比．研究结果表明：珠海天然海积软土的孔隙入口孔径分布为主单峰分布；当应力水平小于结构屈服应力时，其孔隙入口孔径分布和微观结构与应力水平无关；当应力水平达到结构屈服应力时，大中孔隙（200nm）的含量明显减少，而小孔隙（20-200nm）含量则基本不变；在屈服后阶段，小孔隙含量锐减，整体孔隙空间的孔径趋于均匀．最后，初步分析了珠海海积软土和Regina黏土孔隙分布差异的原因是颗粒组成分布和黏土矿物成分的不同．

In this study, the mercury intrusion porosimetry （MIP） tests were performed on the natural marine clay to investigate the relationship between the change in entrance pore size distribution and the applied stress level. Quantitative analysis was made on clay mineral content of Zhuhai clay through X-ray diffraction tests （XRI））. In addition, the measured data was compared to the experimental data obtained Regina clay,Canada. The results show that the entrance pore size distribution of marine clay in Zhuhai demonstrate a continuous unimodal distribution. And the entrance pore size distribution varies little when the stress level is smaller than the gross yielding stress, but changes significantly when the applied stress is in the vicinity of the gross yielding stress. In the latter case, the large pores（ r〉2 000 nm）and the medium pores（2 000 nm〉 r 〉 200 nm） become smaller while the micropores（200 nm〉 r〉20 nm）vary little. When the applied stress is larger than the gross yielding stress, micropores space volume decreases rapidly, and the pore size gradually becomes uniform with the increase in applied stress level. Finally, the differences in pore size distribution between Zhuhai clay and Regina clay can be attributed to different clay content and mineral.